Anaesthesia for pyloromyotomy in infancy

Diagnostic Accuracy of Acid-Base Status in Infants with Hypertrophic Pyloric Stenosis

Background: Hypertrophic pyloric stenosis is a condition in newborns in which the hypertrophic pyloric muscle causes gastric obstructive symptoms of progressive vomiting leading to hypochloremic hypokalemic metabolic alkalosis. The main aim of the research was to assess whether, based on the acid-base status, we can distinguish newborns who vomit due to pylorostenosis, compared with newborns who vomit for other unspecific reasons. Methods: The electronic records of patients in the hospital information system treated under the diagnosis Q40.0 (Congenital hypertrophic pyloric stenosis) (n = 69/included in the study = 53) in the period from 1 January 2014 to 1 January 2022 were reviewed retrospectively. For the purposes of the control group, the electronic records of patients treated in the emergency department with a diagnosis of R11.0 (Nausea and vomiting) (n = 53) without an established cause were randomly reviewed. In addition to the main aim, other research outcomes were to determine differences between groups in the following variables: duration of symptoms, family history, birth (preterm, term, post-term), birth weight, weight during examination, difference between birth weight and weight during an examination, type of vomiting, the thickness of the muscle wall and its length, and to calculate whether there is a correlation between the thickness and length of the pylorus muscle and the duration of vomiting in relation to variables from acid-base status. Results: In relation to the variables of interest between the groups, statistically significant differences were observed in the duration of symptoms (Mdn 4 vs. 2 days, p = 0.002), weight at examination (Mean 3880 vs. 4439 g, p = 0.001), difference in weight between birth and examination (Mean 374 vs. 1010 g, p < 0.0001), and type of vomiting (explosive 45 vs. 22, p = 0.023). In the acid-base status between the groups, a statistically significant difference was recorded for pH (Mdn 7.457 vs. 7.422, p < 0.0001), bicarbonate (Mdn 25 vs. 23 mmol/L, p = 0.000), total carbon dioxide (Mdn 25 vs. 24 mmol/L, p = 0.011), base excess (Mdn 0.8 vs. −1.3 mmol/L, p = 0.000), potassium (Mdn 5 vs. 5.3 mmol/L, p = 0.006), ionized calcium (Mdn 1.28 vs. 1.31 mmol/L, p = 0.011), and glucose (Mdn 4.5 vs. 4.9 mmol/L, p = 0.007). Regardless of the group, the correlations between the duration of vomiting (r = 0.316, p = 0.021 vs. r = 0.148, p = 0.290) and the thickness (r = 0.190, p = 0.172) and length (r = 0.142, p = 0.311) of the pylorus muscle in relation to pH did not exist or were weak. Conclusions: In a world where radiological methods are not equally available everywhere, with promising acid-base indicators, prospective multicenter studies and meta-analyses must be pursued in the future in order not to miss the possible much greater diagnostic potential of acid-base status.

Serum electrolytes and capillary blood gases in the management of hypertrophic pyloric stenosis

The purpose of this study was to assess whether the concentration of serum chloride and other variables, namely serum sodium, potassium and bicarbonate, can be used to predict metabolic acid-base status in infants with hypertrophic pyloric stenosis (HPS) and to assess whether such a prediction is influenced by the state of hydration. One hundred and sixty-three infants with HPS who had at least one set of serum electrolyte and capillary blood gas estimations performed after admission were studied retrospectively. A further 25 infants who had their electrolyte and blood gases measured after at least 12 h of rehydration and correction of the serum sodium and chloride abnormalities were studied prospectively. Stepwise multiple regression analysis, using standard bicarbonate as the dependent variable, revealed serum chloride concentration to be the most powerful independent predictor of standard bicarbonate level (r = -0.69, P less than 0.0001). Other variables did not improve the correlation significantly. In the retrospective study of untreated patients, the calculation of a 90 per cent prediction interval for the model indicated that if the serum chloride level is less than 96 mmol/l, one could be 95 per cent confident (one tail) that the patient was alkalaemic. To be 95 per cent confident that the patient was not alkalaemic, the serum chloride level would have to be greater than 121 mmol/l. The prospective study found that following rehydration a serum chloride level greater than or equal to 106 mmol/l more accurately predicted absence of alkalaemia. We conclude that predictability of acid-base status from measurement of serum chloride depends on the state of hydration of the patient.

Plasma chloride and alkalaemia in pyloric stenosis

Fifty infants with infantile hypertrophic pyloric stenosis were studied prospectively to evaluate the reliability of plasma chloride estimation in the assessment of the acid-base status on admission and during correction of alkalaemia. Four cases were subsequently excluded because of a breach of the study protocol, leaving 46 cases in the study. Seventeen (37 per cent) were normoacidaemic on admission; 13 had plasma chloride concentrations of greater than or equal to 106 mmol/l and four had chloride concentrations of 100-105 mmol/l on admission. Twenty-nine (63 per cent) were alkalaemic on admission; six cases had chloride concentrations of 100-105 mmol/l and 23 cases had concentrations of less than 100 mmol/l. Of those 29 cases requiring correction of alkalaemia, normoacidaemia was achieved at a plasma chloride concentration of greater than or equal to 106 mmol/l in 21 cases (72 per cent) and at a concentration of 100-105 mmol/l in eight cases (28 per cent). Plasma chloride is a reliable parameter in the assessment and correction of alkalaemia in infantile hypertrophic pyloric stenosis provided that a concentration of at least 106 mmol/l is the goal.